Yotam Ottolenghi's tahini and halva brownies: 'Chocolate really can be all things to all people.' Photograph: Johanna Parkin for the Guardian. Food styling: Claire Ptak

One minute you think every flavour combination possible has already been tried, then another one turns up. Take chocolate, which has a remarkable ability to pair with just about anything: from almond to anise, banana to bacon, cardamom to cauliflower; you could go through the entire alphabet and back again without running out of complementary ingredients. It’s far easier to come up with 40 ways with chocolate than to do the 40 days without that many people recently endured for Lent.

The sheer range of chocolate bars on offer these days – whether the 60p one from the corner shop or the luxury block that dazzles with an on-trend flavour combination and high-percentage cocoa solids – combined with the rise of the artisan chocolatier, might all seem rather 2015-ish, but what goes around, comes around. The dedication of entire cafes, patisseries, even restaurants to chocolate is a very old tradition. Chocolate-drinking houses were fashionable in London at the end of the 17th century: the famous Garrick Club, for example, began life as The Cocoa-Tree Chocolate House, while White’s, the capital’s oldest and most exclusive club, was originally White’s Chocolate House way back in 1693. (So popular were they Charles II once banned them for being hotbeds of radical politics.)

Chocolate really can be all things to all people: sweet, savoury, smoky, spicy, creamy, nutty or fruity. It starts off as a bitter, astringent and aroma-free bean that undergoes an epic transformation (through fermentation, drying, roasting and grinding, among other things), before emerging full of complex flavours and an infinite pairing potential. Here are just three.

Tahini and halva brownies

The cooking time is crucial if you’re to get the desired balance between cakey and gooey, but it can vary depending on both your oven and where you put your brownie tray. The difference between a cooking time of 18 and 22 minutes can be significant, so do stay alert. These keep for up to five days in an airtight container. Makes 20 brownies.

Heat the oven to 180C/350F/gas mark 4. Quarter-fill a small saucepan with water and place on a high heat. Bring to a boil, then reduce the heat to medium and sit a heatproof bowl on top of the pan, making sure its base does not come into contact with the water. Put the butter and chocolate in the bowl, leave for about two minutes, to melt, then remove the bowl from the heat and stir until you have a thick, shiny sauce. Set aside to come down to room temperature.

In a large bowl, whisk the eggs and sugar until pale and creamy, and the whisk leaves a trail behind it – about three minutes with an electric whisk, longer by hand. Gently fold the chocolate mix into the eggs – don’t overwork the mix – then fold in the flour, cocoa, walnuts and three-quarters of a teaspoon of salt. Pour into a 21cm x 31cm baking tray lined with parchment paper and spread out into an even layer.

Use a spoon to insert tahini into the brownie mix in about 12 places, then use the back of a clean spoon to swirl it a little through the mix – not too much: you want it uneven. Dot the halva on the surface, pushing it down a little so that it is well submerged but still visible.

Bake for about 20 minutes, until the top is crisp and the middle still has a slight wobble and is gooey inside: check after 18 minutes (see introduction). The brownies may seem a bit undercooked at first, but they will firm up as they cool down. Cut the baked brownie into 20 pieces and serve warm-ish (and gooey!) or at room temperature (and not quite so gooey).

Warm chocolate and hazelnut sauce with vanilla ice-cream

Normally, it’s the ice-cream that’s the star, but not here: this sauce is worthy of all the attention. It can be made in advance and kept in the fridge, too. Serves six.

Heat the oven to 140C/285F/gas mark 1. Spread out the hazelnuts on a baking tray and roast for 15-20 minutes, until brown and crunchy. Remove and, once cooled, transfer half the nuts to a food processor and blitz fine. Roughly chop the other nuts, and put both in separate bowls.

Put the condensed milk and cream in a small pan on a medium heat. Cook for two minutes, stirring, until it starts to steam, then take off the heat before it boils. Stir in the oil and both chocolates, until melted, then add all of the ground hazelnuts and half the chopped ones. Stir in the milk to combine – you’re after a sauce the consistency of thick pouring cream, so add a bit more if need be. If serving at once, return to a low heat for two minutes, to warm through; otherwise, refrigerate until needed (in which case, you’ll have to reheat gently before serving).

Divide the ice-cream between six bowls and pour over the warm sauce. Drizzle with Frangelico, if using, and serve at once with the remaining nuts sprinkled on top.

The combination of cinnamon, chillies and chocolate give this sauce a rather Mexican, mole-like air; the pink peppercorns, on the other hand, are untypical. Either way, this is a rich dish that’s great for an Easter weekend feast. I like it with mashed potatoes. Serves four.

Season the chicken legs with three-quarters of a teaspoon of salt and a good grind of pepper. On a high flame, heat the sunflower oil in a large saute pan for which you have a lid. Add half the chicken and sear for six to seven minutes, turning once halfway through, until deep golden-brown on both sides. Remove from the pan and set aside while you repeat with the remaining chicken.

Add the onions and garlic to the empty pan, and cook on a medium-high heat for 12-15 minutes, stirring often, until the onions are soft, dark and caramelised. Add the tomato wedges, cinnamon, peppercorns, dried chillies and a quarter-teaspoon of salt, cook for four to five minutes, stirring from time to time, then pour the brandy over everything. Cook for two minutes, then return the chicken to the pan with the wine, stock and 300ml water, turn down the heat to low, cover and simmer for an hour.

Lift out the chicken pieces, turn up the heat and leave the sauce to bubble away for 20-25 minutes, until thick and reduced to a quarter of its original volume (ie, you should have about 500ml left in the pan at the end). Remove and discard the cinnamon and chillies, stir in the chocolate and spinach, and cook for two minutes, stirring. Remove from the heat and set aside.

Once the chicken is cool enough to handle, pick all the meat off the bones in 5cm pieces (like so many cooking jobs, your hands are by far the best tool for doing this). Gently stir the meat and pine nuts into the sauce, and serve at once with a generous spoonful of soured cream on each portion.